One of my sons did that in college. Multiple coils with timing or sensor Ed switching between them. Less than impressive.
Sent from my iPhone > On Nov 3, 2019, at 9:27 PM, Ken Hohhof <af...@kwisp.com> wrote: > > > Good sleuthing. > > Now I’m wondering how long it would take high school students to connect a > battery to the coil and build a gun to shoot neodymium magnets. > > Next project: railgun. > > > From: AF <af-boun...@af.afmug.com> On Behalf Of ch...@wbmfg.com > Sent: Sunday, November 3, 2019 2:38 PM > To: AnimalFarm Microwave Users Group <af@af.afmug.com> > Subject: Re: [AFMUG] OT: Induction coil voltage > > This site shows the coil they are using. Lots of turns of small gauge wire. > The gauge is not important but the number of turns is. > > https://www.sciencebuddies.org/science-fair-projects/project-ideas/Phys_p097/physics/high-speed-magnets-faradays-law-lenzs-law > > From: Mark Radabaugh > Sent: Sunday, November 3, 2019 8:20 PM > To: AnimalFarm Microwave Users Group > Subject: Re: [AFMUG] OT: Induction coil voltage > > An old motor or speaker will have a decent amount of enameled wire it it that > you can use. Scrape or melt the enamel off where you want it to conduct. > > Use two LED’s in parallel with the anode opposite directions and you should > get alternating lights when you shake it. > > I wouldn’t worry about the meter - if it’s digital it will be too slow to > show you much. > > Mark > > > On Nov 3, 2019, at 2:54 PM, ch...@wbmfg.com wrote: > > > The magnetic field from an electromagnetic is proportional to the turns and > the current. > > So the inverse is also true. You have a fixed amount of magnetic flux, the > current will be proportional to the number of turns. It is called the > ampere-turns ratio. Lots of turns of 30 gauge will be good. 30 gauge is > common as it used to be used for wire wrapping. Also make sure the magnet is > oriented such that its field cuts the coils at right angles. I would not > worry so much about the voltage. You want 10 mA if you can get it. > > https://en.wikipedia.org/wiki/Ampere-turn > > From: Adam Moffett > Sent: Sunday, November 3, 2019 5:51 PM > To: af@af.afmug.com > Subject: Re: [AFMUG] OT: Induction coil voltage > > I'd bet I have 20-30 turns of 16ga wire....that's just what I happened to > find first. I could tear apart some CAT5 and use the 24ga inside so I can > get more turns in the same area. Or I can find something with a transformer > inside and unwind the super skinny wire on it. I just don't know to what > extent I need to go to make this thing work. > > And yeah it's not obvious in the picture I sent, but you're supposed to > connect the two LED's together short leg to long leg so that one of them > lights up when you drop the magnet North first and the other lights up when > you drop it South first. > > I'd wondered about the length of the pulse too. It's a cheapo digital > multimeter. It does not read the same on each drop of the magnet. When I > say it read 30mV that's just the highest number I saw after several drops. > > -Adam > > > > > > On 11/3/2019 12:40 PM, Ken Hohhof wrote: > I would think yes, although it seems the electrical pulse will be very brief > and I’m not sure you’ll be able to measure it with a meter. Also have you > determined the polarity of the DC generated or tried hooking up the LEDs both > directions? > > In any case, I’d think wrapping the entire length of the cardboard tube with > wire would make the LEDs light up for a longer time and be more visible. > > How many turns do you have on it now? > > From: AF mailto:af-boun...@af.afmug.com On Behalf Of Adam Moffett > Sent: Sunday, November 3, 2019 11:20 AM > To: af@af.afmug.com > Subject: [AFMUG] OT: Induction coil voltage > > I wanted to do this science experiment with the kids. My problem is my LED's > don't light up. It's from a discontinued textbook. Apparently they sold a > kit with the materials for all the projects, but that's no longer available > so I'm scrounging in the garage. > > I put a volt meter on the rig and I was only getting 6mV when I dropped the > magnet. I doubled the number of coils on the tube and then doubled the number > of neodymium magnets and I'm getting closer to 30mV now, but I need closer to > 2V to light up an LED, so I'm wondering what would increase the voltage by > two orders of magnitude. Is it based on the number of turns in the coil? > > > > <image001.png> > > > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com
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